Distribution characteristics of fluoride and aluminum in soil profiles of an abandoned tea plantation and their uptake by six woody species

Distribution characteristics of fluoride (F) and aluminum (Al) in soil prof iles of an abandoned tea plantation in Hong Kong and their uptake by six wo ody species namely Camellia sinensis, Melastoma affine, Sterculia lanceolat a, Ardisia crenata, Acacia formosa and Machilus thunbergii were investigate d. C. sinensis accumulated both F (656 mg/kg in the leaves) and Al (8910 mg /kg in the leaves). M. Affine only accumulated Al (9932 mg/kg in the leaves ), while S, lanceolata A. crenata, A. formosa and M. Thunbergii were Al (26 -115 mg/kg in the leaves) and F (20-25 mg/kg in the leaves) excluders. Wate r-soluble F and Al contents accumulated in surface soils (especially 0-3 cm ) and decreased with depth along soil profiles: A layers (2.0 +/- 0.6 and 3 1 +/- 5.8 mg/kg) >B layers (1.5 +/- 0.2 and 27 +/- 3.5 mg/kg) >C layers (1. 3 +/- 0.2 and 20 +/- 2.7 mg/kg), respectively. The water-soluble, NH4Ac-ext ractable and HCl-extractable F in soil profiles were significantly correlat ed (P < .01). F concentrations in all soil layers (n = 51) of soil profiles (n = 17) were significantly correlated (P < .01) to Al concentrations in t erms of water-soluble Al/F HCl-extractable Al/F and NH4Ac-extractable Al/F, due to the formation of AI-F complexes in soil. F contents extracted with deionized water (pH=6.68), 1 mol/l HCl and 1 mol/l NH4Ac in soil could be u sed to predict F concentrations in the leaves, stems and roots of the six p lants. (C) 2001 Elsevier Science Ltd. All rights reserved.